Clicking/Juddering from behind dashboard when struggling/failing to start.

[Benny06]

I've had battery issues since buying the 182 after having the original battery replaced when it died. It was replaced with an 063.

Whenever it's going to sruggle to start or fail to start after turning the ignition on and waiting for the serv lights etc to go out I can hear this 'clicking' and 'juddering' from behind the dashboard, more specifically on the driverside. I don't know what this is or if it has anything to do with it?

I suspect the alternator might not be charging the battery. This usually occurs then I either have a jump start or jump myself off the battery charger we have and then it's fine for another few weeks.

I'm off to K-tec this weekend but don't think they'll have time to look as I'm there for a remap and exhaust adjustment. JMS is much closer to me so was going to pop it down there.

Any thoughts welcome.

Benny

 

[oliver9523]

Sounds pretty much the same as what used to happen to my old MX-5. I think it was because the battery voltage was too low so the relays were clicking on/off.

The battery had a high enough voltage to turn the relays on but as soon as they came on, creating extra load, the voltage across the battery dropped and the relay turned off, load dropped voltage came back up, relay clicks on, load goes up, voltage drops...etc... etc...
Mine was due to just going back and forth to work everyday in the winter with the heater and lights on. As it was a short journey it never really charged the battery.

I agree that it's probably the alternator, could also be some relay sticking on. Start her up, turn everything on, turn it off and listen for a faint whine. Had this recently with a MR2.

 

[Benny06]

Thanks for the reply.

Where should I be listening for a faint whine? where the relays are behind the dash? or in the engine?

What was the fix for your MX5? I know the batteries in the CS's are too small for the size engine. I know that short journeys can kill a battery pritty quickly as in a year or 2 and don't have a problem buying a new battery annually if need be but surely a new battery shouldn't be going flat every few weeks?

My headunit is wired onto the ignition so can't stay on. However while i usually wait for the lights to go off before turning her over the AC has come on and as has my headunit.

 

[oliver9523]

Sorry, not sure where to look tbh. I fixed the mx5 by showing it some nice long back roads at the weekend to give it a top up... "yes officer...? oh I was just giving my battery a good hard charge "

Here's some info I found when testing the MX5, get a voltmeter and put it across your battry terminals with the IGN off. The following gives a rough idea of battery capacity...

Open Circuit Voltage(v) Capacity(%)
11.89 0%
12.06 25%
12.26 50%
12.45 75%
12.65 100%

Then fire up the engine, get someone to fast idle it at about 2000rpm, put the meter across the battery again and it should be up at around 13.5-14.5v if the alternator is charging it. Less and it's not being charged properly and if it's much more the charge regulator might be playing up and damaging the battery.

If you're feeling really geeky
- open excel
- type in cell B1 "=(1.3065*A1 - 15.515)*100" without the "
- then put your battery reading in cell A1
- an estimated battery capacity will be shown in cell B1

 

[Benny06]

Thanks for that. I'll get them to have a check of it tomorrow and if it still persists then I'll have my alternator looked at.

 

[Benny06]

I did hear a feint whine that you mentioned when leaving work today.

I'll see what K-tec say and update this thread for anybody else that might have the same problem.

 

[Benny06]

After having the doors open and ignition on whilst having the remap done today it almost didn't start!

Had the RAC out to test the battery. Supposed to hold around 400 EN only holding 200, apparently. Despite having a green light. K-tec check the voltage & alternator for me.

New battery fitted, first time and it springs into life. Very pleased